Nicotine administration in humans is known to sharpen attention and to slightly enhance memory. Now scientists, using functional magnetic resonance imaging (MRI), have identified those areas of the brain where nicotine exerts its effects on cognitive skills.

Their findings suggest that nicotine improves attention in smokers by enhancing activation in the posterior cortical and subcortical regions of the brain--areas traditionally associated with visual attention, arousal, and motor activation. This study provides the first evidence that nicotine-induced enhancement of parietal cortex activation is associated with improved attention.

The investigators used functional MRI to visualize nicotine's effects on the brain during a rapid visual information-processing (RVIP) task -- a task that requires sustained attention and working memory. Fifteen smokers with and without a 21- mg transdermal nicotine patch performed the RVIP task while undergoing MRI screening. The subjects performed the RVIP task twice--once with a placebo patch and once with a nicotine patch--and were scanned during each session. They smoked their last cigarette 15 minutes before performing the RVIP task.

When smokers were given a placebo patch for the first scan and a nicotine patch for the second scan, there was improvement in task performance between the two scans. When smokers were given a nicotine patch for the first scan and a placebo patch for the second scan, there was no difference in their performance, suggesting that nicotine and practice interact.

Study findings also suggest that nicotine helps focus attention on task demands by shifting cognitive resources from less "used" parts of the brain to regions required for task performance.

WHAT IT MEANS: This study adds to the understanding of the effects of nicotine on the brain. Such understanding helps explain both nicotine's addictive properties and potential therapeutic applications.

Dr. Elliot A. Stein, Neuroimaging Research Branch, Intramural Research Program, NIDA, and colleagues from the Medical College of Wisconsin and the Institute of Psychiatry in London published the study in the October 24, 2002 issue of Neuron.